U.S. Pat. No. 5,525,843 discloses a seat occupant detection system that uses a seat heater element as an electrode of a capacitive sensor, wherein a pair of relay activated switches are used to either isolate or connect the heating element from or to the associated current supply and ground, wherein the heating element is isolated when sensing the occupant and is otherwise connected when heating the seat. One potential limitation with such an arrangement is that relay controlled switch elements may not be sufficiently reliable for safety applications, such as controlling the actuation of a safety restraint system.